Air springs or air bags have been used in front or steer axle suspension systems in the prior art. The main advantage to air sprung suspensions is the lower spring rate of the air springs can provide a less harsh ride than conventional leaf spring front suspensions. One of the problems with air sprung suspensions is that the air springs in and of themselves do not provide any lateral support such as a conventional leaf spring suspension which is engaged to the chassis through shackles. To overcome this lack of lateral support, most manufacturers include a lateral control rod or a tracking bar or rod. The tracking bars are typically attached to a sprung component at one end such as the axle and to an unsprung component at the other end, such as a frame rail of the chassis. While the tracking bars provide lateral support, there are three drawbacks to their use in a vehicle. The tracking bars add extra weight to the chassis. The second drawback is that the tracking bar poses clearance problems with power train and driveline components on front engine vehicles. The third drawback is that the tracking arm will swing through an arc inducing some lateral displacement of the axle relative to the chassis. This third effect can cause the vehicle to exhibit yaw and other undesirable handling characteristics.
A proposed alternative to the tracking arms is the use of shackles at the rear portion of the trailing beam. The shackles would allow for vertical but not lateral movement of the trailing beam. The rear shackle for the trailing beam acts as a vertical link. A separate vertically mounted shock absorber installed between the chassis and a sprung component such as the trailing arm dampens the vertical movement allowed by the air spring. The drawbacks of this design are the mounting geometrics required for use of the separate vertically mounted shock absorber.
To date, a front or steer axle air suspension without the use of a tracking arm and without installation geometry drawbacks has not been proposed.